【Objective】 Currently endothelial cells (EC) derived from stem cells for therapeutic vascularization is limited by lowefficiency

studies show that transforming growth factor β1 (TGFβ1) participates in the regulation of differentiation of EC but is variant for diversity of receptors and context dependent. In this study

we focused on the relationship between TGFβ1 main typeⅠreceptorALK5 and EC differentiation from bone marrow mesenchymal stem cells (rBMSC) and its application to tissue engineered blood vessel (TEBV). 【Method】 CD31- rBMSC were acquired by adherent cultivation and flow cytometric sorting and were induced 14 days via VEGF

bFGF

and EGM2 BulletKit as standard control. ALK5 signaling activated by TGFβ1 or inhibited by SB431542 for different phases were treated as experimental groups; kinetics expression of endothelial cell markers like vWF

KDR were detected by immunofluorescence. Flow cytometry analysis of CD31+ percentage of each group to evaluated induction efficiency carried out after 14 days. In addition

vascular formation capability of EC was verified by in vitro experiment. Finally

differentiated ECs were seeded on acellular matrix vascular to construct TEBV. 【Results】 According to the expression of ECs markers

differentiation of MSC can be divided into two stages

vascular progenitor cells differentiation from MSC before the 7th day and ECs differentiation from vascular progenitor cells since the 7th day. Compared with the standard group

the percentages of activated ALK5 (VFT groups) at early phase and inhibited ALK5 (VFS group) at later phase were 7.7 folds (P = 0.006) and 1.8 folds (P = 0.013)

respectively. Furthermore

induced cells were shown to have in vitro tubeforming potential function and could be applied to intimal layer reconstruction of TEBV. 【Conclusion】 In differentiation of EC from MSCs

ALK5 signaling is stage dependent: At early phase when MSC differentiate into vascular progenitor cells

activation of ALK5 signaling promotes differentiation; While at later phase when vascular progenitor cells differentiate into endothelial cells

inhibiting ALK5 signaling can promote differentiation. The MSC with improved differentiation efficiency into ECs could be applied to tissue engineered blood vessel endothelialization.